The present invention relates generally to pressure-tight assemblies, particularly to a pressure-tight hydraulic assembly.
A conventional hydraulic unit is described in, for example, German Patent Application No. 195 21 510, where an electromagnetic actuator is placed into a housing made of thermoplastic material. The actuator also has a plastic housing part, which is joined to the housing by welding or gluing in a pressure-tight manner.
The present invention has the advantage that the pressure-tight joint can be produced by ultrasonic welding. A sonotrode advantageous for welding. need not vibrate a mass of the functional unit, e.g., a magnet of an electromagnetic actuator, but only a substantially smaller mass of an insert. In addition, the requirements concerning dimensional stability of the housing are less strict. The functional unit may be pre-assembled in the housing, positioned axially and radially, and tested for operability prior to welding.
The present invention provides further advantageous refinements and improvements. It is particularly advantageous if a cover is molded onto the functional unit and the connections for the functional unit are integrated in the cover. Furthermore, for the ultrasonic welding, it is advantageous that the insert be formed on the end face to be welded by two knife-shaped supports, one knife being in contact with the cover and the other knife being in contact with the housing on the gap surface. This ensures that the material deformed by ultrasonic welding can flow into the cavity formed between the knives. Another convenient design of the gap and the insert, whereby splashing, visible from the outside, of the material flowing during ultrasonic welding is avoided, is made possible by the insert having a wider outer ring and a narrower ring supported by the gap surface, the two knives for ultrasonic joining being formed on the narrower ring.